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A036260 Numbers k > 1 such that k mod ord2(k) is even, where ord2(k) is the order of 2 mod k. 3
2921, 3017, 3473, 3479, 5767, 5969, 6167, 6377, 6497, 6913, 7223, 7519, 7567, 7751, 9017, 9271, 10199, 10447, 11431, 11929, 12719, 13439, 13609, 14513, 16583, 17009, 17143, 18631, 18809, 19313, 20737, 21119, 22337, 22351, 22537 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
These are all composite since for prime p, ord2(p) | phi(p) = p-1, whence p mod ord2(p) = 1.
LINKS
MATHEMATICA
Select[Range[3, 23000, 2], EvenQ[Mod[#, MultiplicativeOrder[2, #]]] &] (* Amiram Eldar, Jul 30 2020 *)
CROSSREFS
Sequence in context: A031552 A205253 A251353 * A180651 A180331 A043444
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset corrected by Amiram Eldar, Jul 30 2020
STATUS
approved

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Last modified May 26 22:59 EDT 2024. Contains 372847 sequences. (Running on oeis4.)